The following description relates to a distributed radio frequency identification system and method.
Radio frequency identification (RFID) systems are known and are useful for remote identification of physical objects. The identifier is also referred to as a “transponder” or tag. In most applications, the RFID transponder is in the form of an integrated circuit chip that in its barest form is a silicon die sawed from a silicon wafer attached to the conductive pattern of a substrate. The RFID transponder can have built-in sensors, either within the chip or on the substrate, for sensing or perceiving a stimulus, and transmit a signal based on such sensory operation. The sensors can be analog sensors for perceiving, among many stimuli, pressure, light, temperature, touch, chemical composition, biological composition, etc. The RFID tag transmits signals wirelessly via a radio frequency channel to a central reader.
FIG. 1 illustrates a conventional RFID reader system for receiving signals from one or more RFID sensing tags that may be spatially distributed about an area. The RFID reader system typically includes an RFID reader 102 connected to a number of antennas 104 via cables 106, through which power and data signals are transmitted. Such a configuration may require many expensive cables 106 and antennas 104, especially for interrogating a large number of widely-distributed RFID sensors.
The antennas 104 within an RFID sensor system, or among systems, are tuned specifically for their environment and may add complexity to the system as a whole. Radio frequency transmissions are also usually limited to only a small number of specific carrier signal frequency bands, and the carrier signal is tightly controlled so as to not transmit sideband signals.
These and other aspects of conventional RFID systems can be costly. Several keys to the future proliferation of the deployment of RFID systems lies in reducing the price and complexity of the RFID components and systems.